fatal-signal: After fork, clear hooks instead of disabling them.

Until now, fatal_signal_fork() has simply disabled all the fatal signal
callback hooks.  This worked fine, because a daemon process forked only
once and the parent didn't do much before it exited.

But upcoming commits will introduce a --monitor option, which requires
processes to fork multiple times.  Sometimes the parent process will fork,
then run for a while, then fork again.  It's not good to disable the
hooks in the child process in such a case, because that prevents e.g.
pidfiles from being removed at the child's exit.

So this commit changes the semantics of fatal_signal_fork() to just
clearing out hooks.  After hooks are cleared, new hooks can be added and
will be executed on process termination in the usual way.

This commit also introduces a cancellation callback function so that a
canceled hook can free resources.

1 files changed, 2 insertions, 2 deletions

diff --git a/extras/ezio/tty.c b/extras/ezio/tty.c
index 709b8028..9b05480a 100644
--- a/extras/ezio/tty.c
+++ b/extras/ezio/tty.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008, 2009 Nicira Networks, Inc.
+/* Copyright (c) 2008, 2009, 2010 Nicira Networks, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -263,7 +263,7 @@ tty_set_raw_mode(int fd, speed_t speed)
             return errno;
         }
         s->tios = tios;
-        fatal_signal_add_hook(restore_termios, s, true);
+        fatal_signal_add_hook(restore_termios, NULL, s, true);
 
         tios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);